1. FIELD OF THE INVENTION
This invention relates generally to circuit breakers and more particularly to an electrical distribution system utilizing a novel circuit breaker having internal control and communication circuit means.
2. DESCRIPTION OF THE RELATED ART
Circuit breakers are commonly used for temporary interruption of electrical power to electrical devices (loads). Modern circuit breaker systems utilize a plurality of remotely controlled circuit breakers for programmable control of lighting and other devices in commercial and industrial applications. Selectively opening and closing the various circuit breakers in a system provides energy savings and ease of operation over manually operated circuit breakers.
Remotely controlled circuit breaker systems typically include a circuit breaker load-center or panel having a plurality of remotely controllable circuit breaker. U.S. Pat. No. 4,920,476 issued to Brodsky et al. on Apr. 24, 1990 shows a circuit breaker system wherein the wiring is accomplished by using a patch-board within the load-center. Other systems use hand-wiring between each circuit breaker input.backslash.output and a terminal in a remotely located control means. Such systems are not flexible, in that each time the circuit breaker control requirements change, the wiring and many system components must be reconfigured or replaced.
U.S. Pat. No. 5,231,565 issued to Bilas et al. on Jul. 27, 1993, which is assigned to the assignee of this application, provides an electrical power distribution system which includes multiple remotely controllable circuit breakers, each of which is operable by a control circuit contained within the load-center in at least an open and a closed position. A termination circuit within the control circuit interprets circuit breaker control signals from external switch devices. Data paths are provided for receiving programming instructions and signals from external devices. A switch input data path coupled to the control circuit carries circuit breaker switching instructions to the individual circuit breakers.
The electrical power distribution system provided by Bilas solves many of the problems of the previous systems. However, the wiring, although simplified through a pre-wired bus, is a limiting factor in the number of circuit breakers that can be controlled from the control circuit. Such systems also contain complex control and interface modules in the load-center for controlling individual circuit breakers and for providing communication with external devices, such as a computer.
The above described electrical power distribution systems generally utilize remotely controllable electromechanical circuit breakers, which are caused to open and close by an external control circuit. More commonly used remotely controllable circuit breakers either contain a solenoid or motor as an actuator, which causes a movable contact to move between an open and a closed position. The operation of the actuator is controlled by an external control circuit. An example of a motor operated circuit breaker is found in U.S. Pat. No. 5,180,051, issued to Cook et al. on Jan. 19, 1993, which is assigned to the assignee of this application, and is incorporated herein by reference.
A state-of-the-art electrical power distribution system is available from Square D Company, Palatine, Ill., under the tradename "PowerLink." In the PowerLink system, a plurality of circuit breakers, such as described by Cook, a control module and an interface circuit module are arranged within a panel enclosure. The control and interface modules control the operation of the circuit breakers and provide twoway communications with any external devices, including any remote control and display means, such as a computer. This is because the individual circuit breakers have little or no internal or local circuitry or intelligence, and, thus, they must be used with external control circuits designed to control such circuit breakers.
More recently, attempts have been made to have circuit breakers which have certain internal capabilities. For example, U.S. patent application Ser. No. 08/023,655, filed on Feb. 26, 1993, naming the inventor of this application as a co-inventor and assigned to the assignee of this application, provides a remotely controllable circuit breaker which incorporates a non-volatile memory for storing therein circuit-monitoring, circuit breaker configuration and certain other circuit breaker information. When such a circuit breaker is used in an electrical power distribution, it communicates with the control circuit of such system to store a wide variety of information in the non-volatile memory.
The electric power distribution systems, utilizing any of the above-noted remotely controllable circuit breakers, however, still are very complex, contain complex control and interface circuitry, and contain a complex data bus. Furthermore, when only a few remotely controllable circuit breakers are desired for a particular application, the entire distribution circuit-panel containing the control circuit must be installed, which can be very expensive and for many applications may not be economically feasible.
Consequently, a need exists for an improved electrical power distribution system which overcomes the above-noted deficiencies. The present invention provides an electrical power distribution system which utilizes a novel circuit breaker, which contains local control and communications circuits for controlling the operation of the circuit breaker and for communicating over a common data bus with other circuit breakers within the electrical power distribution system, external devices, and a remote control and monitoring means, such as a computer.